An Unexpected Knock at Katie Thurston's Door Could Change 'The Bachelorette'

SPOILERS for The Bachelorette Season 17 are ahead.

Longtime fans of The Bachelor and The Bachelorette know that there are a few storylines that will quickly add drama to every season: when a contestant declares that another suitor isn't there for the "right reasons," when two feuding stars get to battle it out during a group date that is physical in nature, and when someone shows up unexpectedly at the lead's room to talk.

On Katie Thurston's season of The Bachelorette, all of the aforementioned plot points have happened — and things have been intense at the Hyatt Regency Tamaya Resort. Though viewers thought that Blake Moynes would be the only surprise arrival, a teaser at the end of the July 5 episode suggests that someone else will be making an unplanned appearance at her room.

The drama is already intense on Season 17 with the men adjusting to Blake's arrival and with Hunter Montgomery taking on the villain role, but the final moments of the July 5 episode reveal that those who remain may have something else entirely to worry about.

In the intense sneak peek, a man knocks on Katie's door. While contestants often try to get more time by surprising the lead in their room, her response indicates that the person knocking isn't necessarily there to seek an extra date.

"Holy s--t," Katie says when she opens the door and sees who is behind it.

"The last thing that I ever expected was you," she admits once she sits down with the mystery person.

The clip, unsurprisingly, did not reveal who exactly is coming to surprise Katie. Though the person knocking is seen wearing a white button down and a jacket, when Katie actually opens the door, the unexpected guest is wearing a gray sweater.

While this could have been an editing trick done to make the moment seem more dramatic, there's every chance that Katie will be dealing with more than one unplanned knock at her door before Season 17 concludes.

Though the brief moment in the teaser didn't show much, fans do have a few thoughts about who the person could be. The spoiler site Reality Steve notes that Michael Allio is likely the one who goes to see Katie in her room.

Michael A. has been a fan favorite contender on Katie's season, but the single dad has also been missing his son. The preview also shows Michael A. on a video call with his child, who is visibly upset at his dad's absence.

He could be showing up at Katie's door to leave The Bachelorette early in order to be with his son.

Michael A. may be the most popular guess as to who is surprising Katie, but there are a few other theories circulating.

There is some speculation that one of Katie's real life exes will show up, or that one of her previously-rejected contestants will attempt to make a return.

Another guess is that Katie's past on-screen ex, Matt James, will be making a cameo. The man in the gray sweater looked to be quite tall, and it would make sense, given Katie's shocked reaction.

Many former leads have shown up on Season 17 of The Bachelorette to offer the Washington native some advice. Because Matt knows Katie from their time together on The Bachelor, it would fit that he would arrive to offer her some of his own guidance.

All will be revealed as Season 17 progresses, but some fans simply don't want to wait that long.

The Bachelorette airs on Mondays at 8 p.m. ET on ABC.